Bose has released SoundLink Bluetooth speaker III ($300), the newest edition in its mobile Bluetooth speaker line. Featuring a new design, the SoundLink III boasts up to 14 hours of battery life with its rechargeable lithium-ion battery. SoundLink III has four drivers, two passive bass radiators, and Bose claims digital signal processing improvements allow users to listen to music at louder levels than SoundLink II — reviewed here. Bose is offering…